Q.

The perpendicular distance, of the line x12=y+21=z+32 from the point P(2, –10, 1) is:          [2025]

1 6  
2 35  
3 52  
4 43  

Ans.

(2)

x12=y+21=z+32=λ (say)

Any point on the line is given by

M(x,y,z)(2λ+1,λ2,2λ3)

Also, PM=(2λ+12)i^+(λ2+10)j^+(2λ31)k^

=(2λ1)i^+(λ+8)j^+(2λ4)k^          ... (i)

  PM·n=0

 (2λ1)2+(λ+8)(1)+(2λ4)2=0

 4λ2+λ8+4λ8=0

 9λ18=0  λ=2

  |PM|=32+62+02=45=35          [Using (i)]